A user sends an e-mail but wants to be confident that it will not be read by an automated text scanning program but can be read by the receiver. Known solutions include using Secured Socket Layer (SSL) encryption, which requires prior distribution of signer certificates or other encryption which requires prior distribution of shared/secret keys is cumbersome and not necessarily required in applications that does not concern with the security and privacy of the message. This system proposes a simple encryption of the text and CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) style human only test to accomplish this.
A “CAPTCHA” is a type of challenge-response test used in computing to determine whether the user is human. The process involves one computer (a server) asking a user to complete a simple test which the computer is able to generate and grade. Because other computers are unable to solve the CAPTCHA, any user entering a correct solution is presumed to be human. A common type of CAPTCHA requires that the user type the letters of a distorted image, sometimes with the addition of an obscured sequence of letters or digits that appears on the screen.
The term “CAPTCHA” was coined in 2000 and is trademarked by Carnegie Mellon University. A CAPTCHA is sometimes described as a reverse Turing test, because it is administered by a machine and targeted to a human, in contrast to the standard Turing test that is typically administered by a human and targeted to a machine.